As it is known by one skilled in the relevant art, the use of multiple antennas (at least two) increases the performance of a radio link. For example, an additional second receive antenna can provide link diversity, and then immunity to multi-path propagation effects, such as fading, and interferences. Such a receive space diversity also improves the physical Bit-Error-Rate (or “BER”) performance. A gain of 3 dB in Signal-to-Noise Ratio (“SNR”) can be achieved when signals received from each antenna are uncorrelated; this leads to a still greater gain in terms of BER and Block Error Rate (“BLER”) due to the non-linear behavior of the channel coding gain. So, it has been proposed to make use of receive space diversity in RF receivers, such as the ones used into mobile handsets (or telephones), and notably the in RF receivers adapted to release 7 of the 3gpp FDD_WCDMA standard) features.
Most of the receiver architectures that have been proposed to allow receive space diversity based on two (or more) antennas basically require the full duplication of the entire chain of reception, from each antenna all the way down to the rake receivers, including the two radio frequency (“RF”) modules. More precisely, these known architectures propose the simple concatenation of i) two RF modules, comprising two low noise amplifiers (or “LNAs”), two pairs of quadrature down-mixers, two channel filters, two DC compensation loops, one RF local oscillator (or “LO”) continuous wave synthesizer, ii) two pairs of analog to digital converters (or “ADCs”), iii) two pairs of FIR RRC filters, and iv) two rake receivers.
As the RF processing modules and the ADCs are the most power greedy parts of the receiver, this architecture is fairly power inefficient for two antennas and even more so for three or more antennas. Moreover such an architecture is not cost-effective.